Automatically order and remove duplicates from this PivotTable named set.
mdxLong: An ST_Xstringattribute that specifies multidimensional expression (MDX) of the PivotTable OLAP calculated member. The length of this attribute MUST be zero or it MUST be greater than 32,767 characters and less than 1,073,741,823 characters. If this value is greater than 32,767 characters, the length of the mdxattribute in the ancestor CT_CalculatedMember element MUST be "1" and the first character of the mdx attribute MUST be equal to " ", the space character (0x0020).
The following W3C XML Schema ([XMLSCHEMA1] section 2.1) fragment specifies the contents of this complex type.
See section 5.4 for the full W3C XML Schema ([XMLSCHEMA1] section 2.1).
headers: A CT_TupleSetHeaders element that specifies the MDX unique names of the OLAP hierarchies and the MDX unique names of the OLAP levels specified by this OLAP named set.